Pumps used to extract or express, mothers milk are well known. Breastmilk pumps are adapted to massage the breast to relieve it of its contents of milk, such as for storage in a container for later use by an infant.
Breast pumps typically come in two types: those that are driven off of a motor, and those that are driven by hand, that is, manual pumps (although Applicant's assignee, Medela Inc., markets a MANUALECTRIC pump which is capable of use either as a manual pump or can be adapted for use with a motor drive. See Applicant s co-pending application U.S. Ser. No. 07/053 055 filed May 22 1987). Typically, these breast pumps include a funnel-shaped rigid hood which is emplaceable over the nipple and a substantial portion of the breast. A reduced pressure or vacuum is then intermittently generated within the hood to create a suction which draws the nipple and adjacent breast further into the narrower portion of the hood. This pulling action both massages and constricts the breast in a manner reminiscent of suckling, resulting in the expression of milk into the funnel opening of the hood. The milk then typically flows into a collecting chamber or container for storage for later use or disposal.
The means generally used for generating the intermittent suction within the hood in a manually driven pump is a compressible bulb or preferably a pneumatic piston pump. The latter commonly would include a piston cylinder that is connected to the hood, with a piston mounted for reciprocating movement within the piston cylinder, such as under the driving action of a hand-driven piston rod connected at one end to the piston, with the other end extending out of the rear of the piston cylinder. Further details regarding a breast pump with such a manually driven piston pump can be gleaned from the aforementioned U.S. patent application Ser. No. 07/053,055.